The present invention relates to a shaft for a flexible endoscope comprising a tubular mantle whose outer surface comes into contact with body tissue of a patient during use of the endoscope. Furthermore, the invention relates to a flexible endoscope having such a shaft.
Such flexible endoscopes with a corresponding shaft are known for example having the designation Fiberskop in the catalogue xe2x80x9cEndoskopie in der Tiermedizinxe2x80x9d, 5th edition, 1/95 from Karl Storz GmbH and Co., Tuttlingen, Germany. In addition, fiberscopes, i.e. flexible endoscopes, are also used for various purposes in human medicine, e.g. for diagnosing respiratory passages.
Flexible endoscopes distinguish from rigid endoscopes in that the shaft of a flexible endoscope- has a flexibility such that it can take on a bent, strongly curved or even a loop-shaped form. To achieve the necessary flexibility, the shaft of a flexible endoscope normally consists of a tubular, flexible mantle, which houses the components necessary for the endoscope, such as an image transmission guide, an optical guide, an instrument channel and actuator cables. The tubular mantle normally consists of a synthetic material which is sealed at its outer side for example with one or more layers of polyurethane.
The length of the endoscope shaft, especially in veterinary medicine, can be up to 150 cm or more. In the field of human medicine, the length of the flexible endoscope shaft is normally between 15 cm and 50 cm. The outer surface of the shaft should have good glide properties as far as possible because the flexible shaft must be inserted over most of its length into an often narrow body cavity when treating a patient or an animal. This is achieved in conventional flexible endoscopes in that the endoscopes are provided with a cover lacquer which is as smooth as possible and also consists of polyurethane.
In practice, however, the glide properties of known flexible endoscope shafts have proven to be insufficient in some cases, especially with increasing lengths. In these cases, an additional glide material, for example in the form of a gel, must be used in order to insert the shaft into the body cavity as easily as possible and with as little pain as possible for the patient or animal. The glide properties of the endoscope shaft are basically improved by the use of a glide material. However, a need still exists for optimizing the glide properties of the flexible endoscope shafts as far as possible to be able to treat a patient or an animal as simply or as easily as possible. In the optimal situation, the use of an additional glide material is then no longer needed.
The object of the present invention is therefore to provide a shaft of the mentioned type whose glide properties are improved compared to previously known endoscope shafts. In addition, an object of the present invention is: to provide a corresponding flexible endosocope.
The object is achieved in that the outer surface of the shaft is microscopically roughened. The flexible endoscope according to the present invention possesses a corresponding shaft.
Roughened microscopically will be understood in that the outer surface of the shaft is roughened. to an extent which is not recognizable by the naked eye or by simple touching. Even so, the outer surface of the shaft according to the invention is uniformly rough compared to the known conventional endoscope shafts. The roughening can preferably be achieved by sand blasting, which will be discussed :in more detail below. Basically however, it is also possible to produce microscopically rough surfaces in other ways.
It has been found completely surprisingly that a microscopically roughened surface when in contact with body tissue has distinctly better glide properties than a completely smooth surface, as has been achieved conventionally using smooth lacquer layers. The rough configuration of the outer surface represents a sharp contrast to all previous measures for improving glide properties, which have always had the intention of making the outer surface as smooth as possible. A possible explanation for the surprising phenomenon is that an outer surface results from roughening which has numerous crater-like depressions. Thus the total contact surface of the outer surface with the surrounding body tissue is smaller than that when the outer surface is smooth. Independent of this attempted explanation, the mentioned feature offers a very simple and exceptionally effective possibility to improve the glide properties of flexible endoscope shafts. There is no need to use a glide material when inserting the shaft into a body. Glide materials bear the risk of allergic reactions in the body, which risk is now excluded.
In an embodiment, the outer surface is roughened by sand blasting. The feature has the advantage that the roughening takes place with a simple measure, which is controllable with conventional technologies. This feature can represent the last finishing step in the manufacture of the shaft without substantial effect on the previously performed manufacturing steps. The mentioned feature thus has the advantage that the improvement of the glide properties is particularly simple and inexpensive from the manufacturing viewpoint. A further advantage is that existing conventional endoscope shafts can be subsequently treated, so that a subsequent improvement of the glide properties of existing or even of already used endoscope shafts is possible.
In a further embodiment of the above-mentioned feature, the outer surface is roughened by sand blasting with grains having edges. Basically it is also known to roughen surfaces by sand blasting with bead-like grains, i.e. not having edges. Investigations have however shown that the improvement of the glide properties is predominant and particularly rapid when using grains having edges.
In a further embodiment of the present invention, the outer surface is roughened to have a roughness which is achievable by sand blasting with corundum 0.05 to 0.5 mm. The numbers 0.05 to 0.5 mm represent the grain size in the known manner for the corundum grains used in sand blasting. The use of other grain sizes or also grinding materials other than corundum is however generally not excluded in this embodiment of the invention.
Decisive is that a roughness of the outer surface is achieved which corresponds to that which is achievable with the aid of the mentioned feature. Namely, it has been shown that such a roughness represents a considerable improvement of the glide properties compared to previously known endoscope shafts. On the other hand, the outer surface of the endoscope shafts experience no measurable degradation with respect to sterilizability and thus the repeated use in the treatment of patients or animals. The mentioned feature is a result of empirical tests and represents an excellent improvement of the glide properties compared to previously employed flexible endoscope shafts. Very good results could also be achieved by sand blasting with glass beads 40 to 70 xcexcm or 70 to 110 xcexcm.
In a further embodiment, the outer surface is roughened by etching. The feature has the advantage that the roughening can take place very uniformly in simple manner. In the simplest case, the previously smooth endoscope shaft is simply placed in a suitable etching bath for a certain time. The outer surface is chemically roughened. The necessary etching agent depends on the material used in forming the outer surface. Suitable etching agents are known per se in the prior art.
In a further embodiment, the outer surface is roughened by abrasion. In contrast to sand blasting, abrasion will be understood as a mechanical roughening of the outer surface, which can be performed with a grinding disc, with sand paper or with similar abrasive means connected to a body. The feature has the advantage that the roughening can be locally specific and differentiated, where different locations on the endoscope shaft can be provided with differing degrees of roughness. For example, differing grain coarseness can be used for different regions of the shaft to generate different roughness at different locations and therefore varying glide properties.
In a further embodiment of the present invention, the outer surface consists of a material which is initially glossy and which is then roughened to an extent that it appears dull. This feature is also the result of empirical tests. Tubular mantles for endoscope shafts were employed as known from the above-mentioned catalogue from Karl Storz GmbH and Co., Tuttlingen, Germany. With these known endoscope shafts, the outer surface is formed by a transparent cover lacquer of polyurethane which appears glossy after being hardened. To improve the glide properties, these outer surfaces are preferably roughened to the extent that they appear dull.
The feature has the advantage that it represents a simple and easily controllable criterion for manufacturing endoscope shafts according to the present invention. The production of the present endoscope shafts is therefore possible without greatly interfering with the previously performed manufacturing steps. On the whole, considerable improvements in the glide properties can be achieved with the mentioned feature in simple manner.
In a further embodiment of the present invention, the tubular mantle comprises at least one base layer and a cover layer arranged thereon, where only the cover layer is roughened. The feature has the advantage that any harm to the inner mantle region of the endoscope shaft is avoided. It is also ensured that a frequent sterilization of the components of the endoscope lying within the endoscope shaft is not impaired.
According to a further embodiment of the present invention, the average roughness value Ra of the roughened surface lies in the range of 0.1 to 1.6 xcexcm. The feature has the advantage that surfaces with this average roughness value show particularly good glide properties along the tissue.
It will be understood that the above-mentioned features and those to be discussed below are applicable not only in the given combinations but also in other combinations or taken alone without departing from the scope of the present invention.